The present invention disclosed herein relates to a technology which linearly compensates for nonlinear distortion, and more particularly, to a predistortion apparatus and method, which reflect a memory effect to linearize an output of a nonlinear device.
In a typical communication system, a power amplifier is an essential element for transmitting/receiving a power signal, and is known as one of components that have the important role of an entire communication system in terms of the function or the manufacturing cost.
A power amplifier requires high linear characteristic in order for a transmitting end to amplify a signal without distortion. However, a power amplifier is a representative nonlinear device having nonlinear characteristic as an analog component. Also, as the use of a wideband signal is recently generalized due to enhancement of a data transfer rate, the memory effect where the past input signal is reflected in determination of an output signal is becoming important characteristic of a power amplifier together with nonlinear characteristic.
Since the nonlinear characteristic of a power amplifier causes Inter Modulation Distortion (IMD) and thus interference arises between an adjacent channel and an inband signal, the nonlinear characteristic becomes the cause that degrades system performance.
Moreover, since the memory effect of a power amplifier causes interference between transmission signal symbols, the distortion of a signal may arise.